I use these inside. They are pretty affordable and comfortable. Pretty ubiquitous so I am guessing easy to find in the UK. IncStores - Jumbo Soft Interlocking Foam Tiles - Perfect for Martial Arts, MMA, Lightweight Home Gyms, p90x, Gymnastics, Cardio, and Exercise https://www.amazon.com/dp/B08LW1SZHB/ref=cm_sw_r_cp_api_i_T2ZNFbTVXX39B?psc=1