As an addition to Capt Flam's response, there are full-time 2-year college courses available (Bristol, Newcastle, when I last looked) which will take you through the Part 66 Approved Basic Training Cat B (ie B1 and/or B2) course. This gets you a Basic Training Certificate, and you then need a reduced amount of work experience (3 years, but check, might be wrong) before you can apply for your Part 66 B1 or B2 licence. The full-time approved course includes Practical Training (ie hand and workshop skills) and On the Job training done on live aircraft under supervision.
The tuition cost is probably North of £15K by now, but if you are an EU citizen you may qualify for financial support.
The alternative route is to do the Basic Training Modules exams by Home Study, one by one, while working in a suitable hangar to collect the 5 years work experience you will need on this route. The problem will be getting a job with no workshop/hand skills whatsoever! So the College route may be necessary if you can raise the dosh. Don't forget that until you have the license, and have put a type rating on it (£3K approx) you will not have much earning power.
The Home study route has the extra work experience in lieu of the Practical and OJT elements of the Basic Training 2-year approved course.
BEWARE of Colleges, and Universities which offer "Aeronautical Engineering" qualifications (eg BTech, degrees etc that do not include the Part 66 Approved course. Look for the Part 147 approval required to deliver the Part 66 basic training course.
In order to attract Government funding, most Colleges etc offer a funded course, such as BTech, with the Part 66 Basic Training course as the syllabus. So long as they are Part 147 approved, that's OK. At the end of the course, you can bin the useless BTech certificate or whatever, and keep the Part 147 Basic Training Certificate.
This is because the UK Government does not regard a Part 66 licence as a vocational qualification (!), and the UKCAA is too lazy to go in there,all guns blazing, to put it right.