There used to be a time when whenever a British subject went abroad if he ever got into any trouble he could expect the entire might of the British Armed Forces to come to his aid if required. That does not happen any longer.
The general rule is that while you are traveling abroad you are subject to the laws of the place in which you are located. Accordingly, if anythings happens that becomes the subject of court proceedings those court proceedings will take place in that country, not in England.
To this however there are exceptions.
One is that package holiday tourists have been specifically given the right to complain to the package tour operator about anything that goes wrong during their holiday and to do so in the English legal system rather than having to do it abroad.
This however only applies to package holiday tourists, not all tourists. Tourists, for example, who travel independently or arrange their own transport and itinerary, etc, do not get this protection, only package tours qualify.
There are also special rules under international treaties for things that happen on aeroplanes and ships. Generally speaking, if you're traveling from this country you will be able to litigate any dispute that arises during such journeys in this country.
It is very important though to take detailed legal advice.