There's a 'tariff calculator', on the CICA website, which provides guidance as to the amount you're likely to receive. Because it's on a secure server (with an 'https' address, rather than an 'http' one) the link, below, won't be 'clickable'. You'll have to copy it and paste it into your browser's address bar:
https://www.cica.gov.uk/portal/page?_pageid=115,90972&_dad=portal&_schema=PORTAL
You might be able to find out further relevant information about the CICA scheme by following the links from their home page (which, once again, is on a secure server):
https://www.cica.gov.uk/portal/page?_pageid=115,1&_dad=portal&_schema=PORTAL
Chris