Can’t believe that nobody’s asked your size and shape yet. Cut is everything.
For classic, Jaeger usually have some good buys.
For stylish (if slim fit), Paul Smith at Bicester Village
For good value (if right size) TK Max have a stock of Ted Baker Endurance
For traditional try Austin Reed (they have some updated styles)
If all that fails, go to M&S, always good value, but the cut is a little generous. Next and French Connection also have nice suits at reasonable prices.
Two buttons, flat fronted trousers, blue is always a good choice, but for summer I’d be looking for something in taupe. Finished off with some nice dark brown shoes.
I too recommend a trip to Bicester Village, last time I went I picked up a Paul Smill for £240, down from £650. It’s brown, but I like it.