You will find going directly to the major providers will not necessarily get you anywhere near the best deal much of the time. Its counter intuitive, but that's the way it works.I use them initially for a ball park figure. Then I contact the ones Im interested in directly. Talk Talk have a matching quote for £236 for 100/100 too.
If you are serious about it you are better off approaching several indy aggregators / resellers that can offer you options from tail circuit providers including VM, Openreach etc.
If you are in a major town or city (especially with VM nearby) you will likely have existing fibre and access nodes nearby that can be leveraged.