if you can get 100hp for £4k then that’d be on my list. Fabia vRS? £4k will get you one and it’ll run forever and certainly ticks the reliable and fun boxes. Cheap tax and insurance too.
In a similar vein, 9N Polo GTs might be in your budget?
MX5? Unless they’ve changed the design, neither of my 3 ever had 4 seats 😉
Someone suggested an Ibiza FR – good call.
Might be a squeeze but there must be a fair few mk1 TTs knocking around for £4k. 4 ‘seats’ in them.
Corsa? C shape, SRI? Nice little underrated cars.
TypeR? Or for cheaper running costs, the 1.6 Sport that looks a bit like a TypeR. Loved my old one.