It is normally standard procedure to obtain references from your last employer, although, you have indicated you are from overseas and not worked in this country, can you not provide these from your last employer?? Any employer would enquire, if not, why not?? Overseas companies can easily be contacted by e-mail, therefore they would be suspicious if you weren’t able to supply one without a valid reason.
If as you say and cannot provide a reference from your last employer, can you not obtain a Part time job to obtain this (but, again they would most likely require a reference).
If from Overseas, companies most important questions are if you have a right to work in the UK, NI Number followed by reference.
I hope this information helps confirms the requirements.
Every direct employment or agency job has asked for a reference - Usually to prove you were not in prison or similar.
If you were in full time education, the college/university will do you a generic reference proving dates of attendance.
The Job centre will even provide a reference for the dates you were sick/looking for work.
Not being able to provide any kind of reference, in the UK or abroad will ring some alarm bells for sure and make it much harder/impossible to get any work.