Advice on finding my first job as PC repair technician

I’d like to work as PC repair technician in Slough or nearby.  I wouldn’t mind receiving little pay to start with.  I thought that the best way to find a job would be something like finding some terporary job agency but I cannot find any that deals on these types of jobs, besides online job search websites. 

I have a HNC as Technician in Electronics (in fact, I studied in Spain what is more or less a HNC in the UK: five years training).  I also have some three months experience as desktop/laptop repair in Spain and a recommendation letter.

Could anyone tell me where to find some job agency for these types of jobs?.  I’m not that young any more (I’m fifty).

I’d welcome any advice very much or anything related on how to find this type of job.

Thanks!