Pampers Active fit economy size packs are now on offer. 2 packs for £12. sizes 3, 4, 4+, and 5. This is the "new" active fit. We haven't tried the new ones yet with our little one so cant comment if there's really a difference with the older active fit.
Also New Baby (not sure what sizes, on their website it just lists size 2) and their pulls ups "easy ups" sizes 4,5,6.