QS (used to be called Quality Seconds) do joggers and hoodies up to size 22.
Bon Marche also do quite nice joggers, and they have different leg lengths, which is useful if you are not so tall. I think they also go up to 22.
TK Maxx has a huge range of sporty stuff - lots of ski wear at the moment - and they are also good for trainers.
I have quite a few pairs of the M&S £9.50 joggers. They keep changing the colours and I'm not sure what's available at the moment. Very comfortable, very stretchy, and wash like a dream. Different leg lengths, too. The matching hoodies and tops are very nice but I like mine really long and these are not.
For tops I usually get the pique polo shirts from Cotton Traders. Good colours, wash very well, nice and long, don't cling when you get a bit hot and sticky. Check out their website for special offers and also for their clearance shops (I know there is one in Evesham); also the leaflets which fall out of the Sunday magazines!
Evans does some sports wear, but I find that the legs are too long for me. Tops are nice, though.
Matalan is good for really basic stuff. You can get branded sports bras in there too at a reasonable price.
TK Maxx is great for the brands like Adidas and Nike, Reebok etc., and most of the supermarkets do some good workout wear - Asda is particularly good.
I got all my running gear from Aldi - a fantastic set of running trousers and a windproof running top. I also got running gloves and ear covers (I run outdoors, not at a gym!) and a hi-vis jacket.
If you've got an outlet place near you (I go to Cheshire Oaks or Freeport at Fleetwood) they have sports shops there that have huge discounts. Also some of the sports places like Sports Direct stock things that are last season or a few seasons old and are cheap as chips!