I looked at Lowestoft last year as I'd a wedding to go to there (it didn't go ahead in reality!).
Generally, look at Trip Advisor or Booking.com for decent enough reviews as a guideline. Also there are the usual Travel Lodges & Premier Inns. Plus, there are 1 or 2 hotels linked to the Best Western marketing links which generally are good!
I work in Hotels so use those sources to decide where to stay.