Not a deal or a voucher but I stumbled upon a way to get more ROBLOX when you buy a ROBLOX gift card so this might be useful to someone.
Our Son got a £10.00 gift card for ROBLOX, when he went to add it to his account he had his settings as country=USA, rather than country=UK.
It seems if you choose this option you get 1500 roblox , whereas if you say UK in yoiur settings you just get 1000 roblox.
Once added you can reset your country to the UK again.
This might be useful to someone somewhere hence the post.
Another example of rip off Britain