This is unlikely to be considered reasonable if the alternative is to get a ramp and bell that would cost as little as £30 pounds and certainly under £100.  The equality and human rights commission code tells service providers that they must provide a service for disabled customers that is as close as reasonably possible to the service that they provide for non disabled customers.  Serving people in the street isn’t as close to the experience of non-disabled people as possible. When it’s freezing cold or raining it’s particularly unsuitable. While some people will accept this treatment, it has been found not to comply with the equality act on a number of occasions. Useful case law on this point was provided by District Judge Lettall in the case of  Fogerty v Farjampour (Trading as Pizza Lavita) [Stockport County Court, 6th July 2015]:

“Offering to bring the menu outside and serve the claimant outside – though I am sure, in Mr Farjampour’s mind, well-meaning – actually shows a complete lack of empathy on his part with the entitlement of a wheelchair user to be treated no different to anyone else. Therefore, I am satisfied that there is a breach”

When Royal Bank of Scotland were taken to court for saying it was reasonable to serve a disabled customer from the street this was found not to be a reasonable adjustment and they were ordered to pay £6000 in compensation.