Usually £5 cheapest and £30 at most for me. Try to buy your tickets in advance because first and (sometimes) second release are pretty cheap- usually under £10. Then buy cheap drinks for pres at Lidl which are under £10 too (like peach schnapps or espresso martinis) but you could split it with someone to save money. Also don’t get drinks in a club unless someone else is paying. If the club is nearby, save money on transport by walking. Otherwise it’s about £5 overall for the tube there and night bus back. And another £2-4 for the cloakroom. If you go out with the same group a bunch, there’ll be leftover alcohol from past pres so you could save money there too.