I’m using one of these at the moment, http://www.gooutdoors.co.uk/polaris-mens-rbs-cycling-jacket-p103581 which is wind proof and water resistant, but definitely not breathable.
I’ve got one of these as well, http://www.gooutdoors.co.uk/polaris-rbs-grid-hi-vis-jacket-p286926 which is waterproof and breathable, but a bit bulky when packed and too warm when riding hard.

What’s light, waterproof and breathable in that sort of price range?

Basically what you want doesn’t exist.

I have a slightly older montane cycling waterproof jacket that wasn’t breathable enough, so I took a hole punch and cut some holes in the armpit and down the underside of the arm, now works pretty well.

Normally people ask for the impossible Holy Grail of light, waterproof and breathable but you want it cheap as well??! 😯 😆

have you been a good person this year? ask father christmas to put something under the tree. no seriously if you want breathable you need to save up some money and get something with either gore / e’vent or similar marketing guff in the title. another trick is to not ride so hard that you sweat in the first instance 😉
this item claims to do all what you want but have no experience of it http://www.ebay.co.uk/itm/Cycling-Jacket-Waterproof-Windproof-Jacket-Inside-lining-Cycling-Riding-/261324880816?_trksid=p2054897.l4275

Get yourself down to Aldi tomorrow morning>
https://www.aldi.co.uk/en/specialbuys/our-specialbuy-events/cycling/

https://www.aldi.co.uk/en/specialbuys/thursday-25-september/product-detail/ps/p/cycling-rain-jacket-2/

I always find the best happy medium for what you want is a soft-shell. Any cheap hardshell is always boil-in-the-bag, and absolutely horrible to wear.

Personally I think a decent waterproof is pretty much essential if you actually want to ride a bike in the UK anytime outside June. Spend a bit more and get something decent, you tight ****! 😀

Forget breathable and concentrate on getting cheap with ‘big’ pitzips.

It’s mainly for commuting.
I’m a mechanic and it always seems a bit pointless having a shower after work, then having another one at home less than an hour later, so I tend to ride home oily and have a single dual purpose shower.
It saves time, but my kit gets a bit grubby, which is why I wanted something cheap that I wouldn’t be too upset about wrecking.
It doesn’t need to be top performance either. As it’s only a short ride, I can regulate my speed to regulate my body temperature and sweat output to a certain extent.
Maybe one of those sub £20 ones would be worth a try.

I got a marmot nanowick for £40 from sportspursuit which is pretty good lightweight (130g) sort of breathable. More of an emergency keep in backpocket type of jacket.

Simple answer for shorter rides (works ok on long ones too) is accept getting wet and aim to stay warm while wet, if so there’s cheap kit that works well. Simple showerproofs breathe OK and a thin primaloft or pile based gilet can keep you at a comfortable temperature as long as the shell breathes more than G-tex etc do.
As soon as you want waterproof fabric shell layers it gets expensive. And oil / grease kills it.

Personally I think a decent waterproof is pretty much essential if you actually want to ride a bike in the UK anytime outside June. Spend a bit more and get something decent, you tight ****!

I disagree, I have an expensive Gore one, and I’ve ridden in it once in the last 3 years I think! Soft shell FTW.

One thing we used to do in running was to wear two very thin and light water resistant tops together.

Didn’t get the boil in the bag, its a cheap option, pretty light and near enough fully waterproof (rain gets through after about 1.5-2 hours)
You can wear one layer normally to keep wind chill off and then put on the second layer when its starts to rain heavier.

My current favourite set up, although its not cheap, is to use a Gore ALP-X soft shell set up for normal riding and add a lightweight water resistant top over that when the rain gets heavy. I accept this does not truly answer your original, moon on a stick, question

if it’s only for commuting then a lightweight “packable” waterproof is sufficient – there are a few cheap ones on ebay. as jameso said it only really becomes an issue if you stop and get cold. if it’s gonna get dirty no point spending a packet

Why bother about getting wet? Skins waterproof and few people have ever dissolved! Getting cold is the problem, so layers and not using cotton are 2 very good ways of staying warm when wet.

A study has shown (and my own experience of commuting every day) that in an average year in a part of the UK, if you commute every day you will get wet 7 times. Hardly worth spending £150 on a decent light, breathable waterproof (that isn’t cheap).

I use a cheap running hi viz top. Windproof, not waterproof, but very visible. Cost me about £15 and has lasted 3 years commuting, and gets chucked in the washing machine to remove any of its waterproofing capabilities.

For hilly mtb rides I use a cheap (free with What Cycling weekly or something) Altura thing, or a Berghaus paclite if it’s going to be bad. But I hardly ever wear either, just carry them as ballast or in case…