Just to clarify the law with regard to premises serving food:
There is NO statutory requirement for such premises to provide toilet facilities for their customers. (There are loads of small cafés around London's West End that have no toilets for their customers. Cambridge is much the same). However some local authorities now make it a condition for planning consent, when a new café is proposed, that customer toilets must be provided. Since that can't be retrospective though, that still leaves thousands of cafés operating perfectly lawfully without customer toilets.
Much of the misinformation about the (alleged) requirement for cafés to provide customer toilets stems from a storyline in Coronation Street, several decades ago, where a local businessman tried to stop The Cabin from selling refreshments because they hadn't got customer toilets. Unfortunately the scriptwriter had got his facts wrong but ever since then people have believed that it's a legal requirement!
Unless it's included as a planning requirement, nobody is ever required to provide public/customer toilets. Local authorities aren't required to provide toilets (which is why provision varies so widely across different areas) and even pubs aren't. (There used to be a pub, listed in the Good Pubs Guide, where customers who needed the loo had to walk to the other end of the street and use the council-owned ones).
However, where toilets are provided as a facility for customers (as in nearly all pubs) the law requires that disabled customers shouldn't be discriminated against (unless it's not 'reasonably possible' to provide facilities for them due, for example, to the layout of a historic building).