One series could be the SRGT series, but that depends on what spec the car is. i think they have had a couple of Modsports Davrians racing in the series in the past. Have a look here:
http://www.srgtc.org.uk/
Apart from that there are very few places to race an old modsports type car. All the places it could race would have modern sports cars in.
It is a shame that there are not mroe modsports out racing.