We have built recently too. Although I do have experience in a similar industry, which helped a lot.

You could go either way, with trying to find a block to fit your house or vice versa. What is it about this house that you like? Have you actually been through it? Is it the exterior facade, the outdoor part, the furnishings or the house plan itself?

For us, we couldn't find a "spec home" plan that was just right for us. We did find something similar and made a lot of modifications both to suit our block and to suit our tastes. We found a spec home that we loved the look of the exterior for and went through a number of display homes for ideas on the interiors. This mish mash of ideas became our house.

Once you have sorted out a rough house plan that you want, you can either choose to have it drawn up by a building designer (or architect ($$)) or you can find a spec builder who will do one off designs. We found that many will not (one wouldn't even make a simple modification to their plan, when we were looking earlier on). We got a bit disheartened and thought we had to go with a building designer. However, I was quoted a price for our plans that I found too expensive, given that I am able to produce a reasonably polished plan myself. We then persisted with the spec builder option and found one of a quality I was happy with who would do our plans. As I said they needed little modification, but we did get some good suggestions from their staff building designer.

Either way you will now have a nice plan that you can use to get a budget quote on for the building. With a building designer's plan you can shop it around several builders to get the best price and you will be able to use some of the smaller builders. If you've had it drawn up by the spec builder, you can probably only go with them, although if it comes out above budget, they will be able to tell you where you can cut costs.

From there you can sign a contract and get on with the fun stuff (like selections, lol!)

As for hassles, there were some things, but in the end we got exactly the house that we wanted, so they were relatively minor. However, I do think it was fortunate that I worked in the industry, could ask people for guidance and was able to understand enough to be asking the right questions of the builder. Because we lived close to the site, we visited every day to check on progress and make sure everything was as we had planned. This really paid off when one day they installed the flooring, which was not what we had ordered. Because we could get onto the supervisor straight away, they held off laying the rest of the floor, which saved them some money and us some time. Make sure you get the construction access key and don't let go of it (even if it's the builder's policy that you only keep it a day or a week). It's your property and you should keep an eye on it.

My advice is to be careful about what a lot of builders quote for footings - quite often it is the bare minimum and when they get the soil report back, they up the quote significantly. This can make some people's budget be right off. Find out about footing costs per square metre for houses in a similar area.

Ok, I could go on and on..... sorry! Hope this helps a bit.