Hi,
I can recommend a company who specializes in LHD vehicles who are based on the Nottingham/ Derbyshire border and We have brought and sold several cars from them over the years they do all the paperwork and take all the headache out of buying for you...you only have to pay the suma tax and register at the town hall/ tax office and then factor in the tax you have to pay at alicante for the different ownership as this varies upon the model, engine type and overall value. On our last car which was 12 k we paid close to 900 euro to alicante and I think it was about 80 euros to suma.
Most Spainish car dealers can arrange this all for you but it’s not always practical if you wish to start your journey from Uk.
I had Spainish insurance through Jennifer Cunningham although Iam a Uk resident and iam allowed to drive upto 30 days in any other European country with this so the journey from Uk across France etc is all legal .
Do as much homework as you can and if you deal with the right people you stay correct and legal with no scares at the end of the day!