As TJ said. But if your keen I had good results with Platikote spray enamel from Wilkos. Goes on nice & thick. Limited colour choice, but nice glossy finish that didnt really need lacquering. Cost wise your looking at least £30, & lots & lots of time.
If you can strip it to bare steel, I can get it done matt black for nowt, but it has to be completely stripped as the powder needs an electrically conductive surface to adhere, before baking.
Another vote for enammelling it properly but if you really want to DIY for minimum cost, sand it down with fine wet/dry (No real need to paint stip it IME – just make sure you remove any rust/corrosion and flaking paint), wash it/degrease it thoroughly and then use Plastikote paint on a nice warm day. Lots of thin coats and it’ll be fine.
As above, should only need three cans of plastikote (assuming a standard diamond frame) which IIRC is £12ish from B&Q with plenty of colour choice.
Thanks for the advice I fully appreciate the reasons for doing it properly but it is an old bike that I leave at my parent’s house for when I am at keswick with some surprise spare time. I quite fancy the time spent on a tactile process spread over a few nice evenings.
Result is it will be Sky Blue Plastikote from B&Q.