Jeez, those Jottnar’s are nice. But the price!
As usual – just go to Decathlon – but not necessarily from the Hiking range.
Just got myself one in Belgium (as it doesn’t appear to be here) from the Sailing bit. €90, so £70. Same waterproof-ness, hard to compare on the breathability but no underarm zips (remember, all those jackets that put under arm zips in are because they’re not breathable enough). Possibly less breathable due to the nature (sailing) but more than good enough for hiking in.
It’s also a membrane, not a coating (like HyVent etc), so should last longer.
It’s obviously not the best, but for general mooching around, it’s hard to beat.