Just go here and type in your postcode ..
https://www.electricalsafetyfirst.org.uk/find-an-electrician/. I always try to get someone local for doing work on my home, so I can get hold of them easier if I need to. You shouldn't need a recommendation for a simple job as doing security lights, just one that's certified and can give you a certificate to prove it has been done by one.
Or, depending on if it can be mounted in a suitable location and the lumens is enough, some solar powered lights can do the job and you can do this yourself ...
https://www.thesolarcentre.co.uk/catalog/Solar_Security_Lights_With_Remote_Solar_Panel-106-1.html. If going that route, get the ones with a separate solar panel though and the more you pay the better. I bought two cheap £15 ones from them and unplugged one from the charger about 3 months ago and it still worked 2 months later.