£37+VAT does sound expensive to me. For example, I’ve got an unlimited data deal with Lebarra for £25 a month inc vat, and no contract.
As dovebiker says, you need to work out which provider will give the best reception in your location. You could start by looking here: https://www.signalchecker.co.uk
Then I’d get a cheap ‘pay as you go sim’ to check the specific network/reception before commiting to anything more. Most mobile networks have cheaper brands. (e.g Lebarra actually runs on Vodafone). You may also need to investigate an upgraded router or external aerial to get the top speeds.