When it comes to the foundations of your DIY conservatory, there is no point skimping on them. For a dwarf wall conservatory we recommend that the footings are at least 600mm deep. For a full height design then a very solid and stable purpose made concrete base is the answer. If in doubt about the soil conditions in your area, contact a trusted builder for advice.
Once the base has been correctly constructed the erecting of the conservatory will be easy and you will be secure in the knowledge that, come a few years time, it will still be where you built it!