For vests I use the ones without poppers but with an envelope neck still. Mothercare and John Lewis stock them. For trousers I find M&S are the best (particularly their £4 jeans!). You will find as your ds grows and slims down a bit that the nappy bulk becomes less of an issue. HTH.
I agree with the 'T-shirt' style vests from John Lewis with no poppers.
Loose 'jogging bottom' trousers good. Now it's (supposed to be) summer, I have bought quite a few pairs of cheap 2-3yrs shorts in stretchy material that fit like 3/4 length trousers on my chunky 16month old. Jeans a disaster for us, but he'll have plenty of years to wear those when out of nappies. You need to train you eye to size up trousers when shopping and reject narrow cuts.
Have 1 pair of cut4cloth trs and they are wonderful, but agree pricey. £2-4 joggers from asda or h&m make up for the occasional extravagance.
Next do some great jogger style trousers (but the baggy style leg, not the straight cut). They've always got some in the catalogue, cheap too! I bought some really cute ones in primark recently too - £2 for 2!
I was thinking of buying a pair of the cut4cloth navy drawstring trousers as a special treat as ds2 lives in his brother's handmedowns!
I so wish they had H&M in my town, I bought some stuff whilst on holiday (tho couldnt find any trousers I liked) and it's fab!
Flame, btw, did I thank you for the kiwi lite? I think it arrived just before I went on holiday, but I had it on ds2 this morning and I wondered whether I'd emailed you, I lost track with all the stuff I'd bought that month....If I didn't, thank you