The better training courses are geared towards the type of sailing you intend to do. For example, the RYA scheme have various levels of achievement:
- Day skipper
- for day trips in daylight
- Coastal Skipper
- for sailing in coastal of protected waters
- Yachtmaster Offshore
- for offshore sailing.
Sounds like you are in the last category. The 'zero to hero' course can be done in about 17 weeks I think.
This will give you a certain amount of knowledge and some basic skills but it won't give you much experience. That's achieved by getting out on boats in different sea conditions over a period of time.
I think if I was in your situation, the way I'd go about training is to get signed up for a weekend dingy course to get used to sails wind
and boats, then get involved in the local racing
scene and after a time do one of the national training programmes aimed at offshore sailing.