What is the best way to move a lilac tree that is planted in the ground? I want to put it into a large patio pot, will this be ok?

The lilac is probably too big for a pot by now, the root system would be huge - it took us a massive amount of work to remove one a few years ago, and there was no saving it. You could try taking cuttings, or looking for shoots popping up a little way away from the main plant and dig it up with a little root.

I'm not sure about lavender, but again you can easily take cuttings to have a whole new plant (or 6!).

you could do as madmum says but the shoots or suckers may not be the same variety as the top. they use the common lilac as the rootstock. so if you are happy with this plant go for it.
again the size of the lavendar probably prevents its move so i would take cuttings too.

Thanks for responding so quickly, I am loving this website, as I need as much guidance as possible, I am a total novice!!
In reference to my novice gardener status, can you please tell me the best way to take cuttings? Not sure if the same rules apply to all plants, which is the best rooting powder to use etc etc...

Susie, you ask a big question. It would take several blogs to describe how to take cuttings of all plants. You could go to the local library for a book or, much better, see if there is a local gardening club near you. You will find club members are just as friendly as the subscribers to GOY and one of them will, very likely, actually show you hpw to take cuttings.