Why would it affect your redundancy? nobody would expect you to leave the country to take a job lasting ten weeks? or do you mean it's your present employer sending you, either way I doubt there would be much of a case to stop your redundancy.
I would have thought ( and unless it was already part of your existing job to travel ) that you are quite entitled to refuse the UK job if your present circumstances are such that leaving home is not an option.
OK, so what you are saying is that you want to collect your redundancy and then take the UK job? If the UK job is a different job then there shouldn't be a problem, unless, you employer sees it as the same? The only way to find out is to ask the employer. Collect the redundancy first though.