Many top unis do require certain grades at GCSE, but you do meet the minimum requirements for Warwick, its just the case of checking these requirements across the others unis too,
It wouldn't necessarily disadvantage you but since your A-levels are predicated quite highly, I don't think it will make that great of a difference, just make sure to have a top personal statement and a good reference.
Russel group unis do have tiers, Warwick being the top one out of your list, with (in my opinion) Manchester, Exeter, Leeds, Bristol and Nottingham following behind.
For Law, they need to see genuine interest, a lot of your extracurriculars are good as they show you can keep a good balance, but you would benefit from adding in more law-related activities, especially as law degrees will have a lot of extra reading and is an essay intensive subject. This is what RG unis will be looking for, and if you present this then you GCSEs shouldn't drag you down.