Do not be afraid to lay a new floor simply because you have radiator pipes leading down into the floor. It is easier than you think to do a good job.
The key to making the whole floor look good, including the trickier details, is patience and planning. As with the rest of the floor, it is important to prepare your underlay properly for radiators. Measure the width of the two pipes as well as the distance from the pipes to the wall and mark this on the underlay. Cut this out and place the remaining pieces of underlay between and behind the pipes. If you tape it down, it will stay in place.
The next step is to start with the plank that will be placed next to the pipes. Measure the distance between the wall and the centres of the pipes. Take this measurement and saw the plank along the line; this will be the small piece that eventually ends up behind the pipes. Then measure the distance from the last plank before the pipes to the centres of the two pipes and mark this on the small piece. These are the markings you will use to drill or saw the holes for the pipes.
Then click the long and short pieces of the plank you are working with into place between two other planks and push the small piece firmly against the long one. The whole thing will then be much more stable to work with. Use a butterfly drill or jig saw to drill or saw holes where your marks are. Note that half of the holes should, of course, be in each part of the sawn-off plank. A golden rule for this is to drill or saw a hole with a diameter 16 mm larger than the pipe itself.
Then it is time to lay the planks in place. Start with the small piece that goes behind the pipes. Afterwards, lay the longer piece in front of them. Use a knocking block to knock them into place so they fit tightly. Remember that there is no click joint between the short and the long piece because you sawed them yourself. If you think the hole around the pipe is too large or is not neat enough, you can fill it with silicone to tidy it up.