just a teeny word of caution - I am a GP, and have no axe to grind either way; it is extremely difficult to get a robust diagnosis of Lyme Disease unless you were seen early, in an acute infection, with the typical rash. Also good if you got some serology(blood tests for the bug)
The wikipedia article is pretty good: http://en.wikipedia.org/wiki/Lyme_disease ; I would point out the section that starts 'Chronic Lyme Disease and post-Lyme syndrome' as a balanced discussion of the issues.

Lyme disease is a disorder which creates divisions between scientists, let alone patients and doctors. There is a huge overlap with the Chronic Lyme Disease patients with other unknown-cause fatigue and medically unexplained syndromes, like ME, Fibromyalgia, Post Viral Fatigue, Systemic Candidosis and Chronic Fatigue Syndrome.

Some of the 'patient groups' are ... unusually vociferous. Death threats against sceptical doctors are not unheard of. Even in the UK. The advice from their websites etc is very one-sided; the plural of 'anecdote' is not 'data'.
In some of the chronic fatigue syndromes membership of a patient action group is associated with a worse prognosis; i.e. it takes longer to get better.

On antibiotics: there is NO evidence that 'long term' antibiotics are of any benefit in Lyme Disease.
Short term(2-4 weeks) can help in confirmed or suspected early cases, and in some cases of later diagnosis.

If you did not have a tick, or a typical rash, or a short-lived flu-like illness at onset(even without the rash) you are already very unlikely to have Lyme Disease. It is also not especially prevalent in Wales.
More likely if were out in n the heather + hills of Exmoor or Scottish Highlands AND remember the onset after a bite having been in that area.

Your next problem is that the serology is not 100% accurate; a proportion of the healthy population will have antibodies to Lyme; some people with Lyme don't.

Sorry to be seemingly negative; I am just counselling against looking for a 'hard' diagnosis when it may not be forthcoming. A progmatic approach may be more helpful.
Discuss with your GP whether a referral to a local Rheumatologist, or Infectious Disease Consultant may be of benefit.

Good luck