Hi there, surface engineering is pretty specific and as such you will only find those roles in very large companies, Rolls Royce, Siemans, Bodycote etc. Tribology is even more specific but if you have done some corrosion work (tribocorrosion) then thats starting to get popular within the oil and gas industry (corrosion people tend to get well paid in oil and gas but thats mainly based in Scotland).
I would initially look for material engineer positions unless you go directly to the very large corporations. An alternative idea is that there are some consultancy jobs being banded about in the london area that you could go for. Materials World is an option but linked in and online job recruitment sites work well.
Hope this helps