Hi Jss1ss,
If you are looking to rent then you can check the differences in a property website such as
Property to rent & property for rent in the UK.
It's harder to find details for Reading but Central London will be a lot more expensive. So if they are giving you enough to live in London then you'll be okay for Reading
Reading is so much smaller than London that you won't find much on the cost of living there on the internet (but I don't mind being proved wrong). I hope that someone on here can give you personal info from the area.
Regards,
Karen