Hello Maninad. I haven't read entire thread either but I second what Mojo and others have said that this may be more a problem related to your own career development and trajectory rather than a homesicknessness problem per se. (Glad to hear homesickness abated a bit though!!)
It's so vital to have a role in your own right and not just feel you are an adjunct to what your oh is doing (important a job as looking after yr dc is - don't meant to denigrate that role by any means - but they will grow up fast) It's also important for your dc that their main career is fulfilled and has a bit of life of his own!!
I know isolation can be a very real issue, partic with young dc (and knackering!!), and career projectory is obviously harder/more complicated by living abroad. And it is really hard being such a long way from elderly parents. All this I know from personal experience.
However, however, sometimes living abroad can give you a liberation and a "what the hell, no-one knows me, I can start afresh and be whoever I want to be" sort of feeling. And that can last for a long time when you are an "outsider"
So I would highly recommend that you INSIST on getting the training you need to follow a career path that could make you happy and give you some self-fulfillment (once your dc are old enough). You must make this a priority!! Even if it means arranging to go back to the UK for part of the year and causing huge inconvenience to everyone else. Honestly, it will pay dividends in the future.
Is your German sufficiently good to follow a horticultural course over there? What are your living circumstances? Can you build or get access to a poly-tunnel? Could you possibly collaborate with other eco-concerned locals and start a veg box scheme or some such? Could you study alpine flowers and take English visitors on tours of the locality? Dunno - just throwing out ideas!!!
Sorry to sound preachy but I am going through the same as you but 5 yrs on! (And I still need to follow my own advice!!) I've been in Brussels since 94 and had one dd 8 yrs ago. I don't hate it as much as RushingRachel (my postman is wonderful since bunging him a wodge of money the Christmas we moved in and every Christmas since, have had loads of contact with health service - all truly superb - oh and btw fennel tea IS very good for settling baby's digestion!!) BUt, but, a lot of what you both say strikes a chord with me. It is isolating being the outsider all the time and however well you speak the native language(s), you never quite get to the same level of nuance/colloqualism/humour (or lack of) as your colleagues/neighbours/friends which can be really exhausting and demoralising.
My dh and dd are both very happy and fulfilled here and I am much happier that dd is being brought up and educated here than in UK (she is tri-lingual aged 8). However, however, I feel as if my career is down the lavatory and I'm really unhappy aobut it and frankly I haven't found a solution yet, which is making me feel very down.
LikeRushingRachel, nor do I want to be responsible for moving my entire family back to UK. If I'm honest, although I love the initial few weeks of rushing around to see family & friends, buying pants in M&S and gorging myself on salt and vinegar crisps 
, I feel an outsider in the UK now as well!! I don't like the drinking culture there, and the bread gives me a stomach upset!! I also find the Belgian culture much warmer towards dc.
So - this is just a very long-winded way of saying - get yourself training and a job and a role in life that is self-fulfilling (ideally that will bring you in to contact with other like-minded people). If your childcare duties are too heavy right now, then start planning or working towards your new life - this will give you an incentive to keep going. Be selfish and make this a priority!!!!
Good luck!