There are "hidey holes" all along the south shore of Wales, so getting from Swansea to Bristol (Portishead) is no trick at all navigation-wise. BUT the tides, and consequently the
current, in Bristol Channel command respect. The distance from Swansea to Portishead is about 50 NM, and the Nomad under
power is good for 4 knots, so IF there were no
current, the trip would take you 50/4, say 12 hours. That would be a long day for a
novice, so plan on taking break about halfway. And just where would "halfway" be? Well that depends on the tides and the consequent current. Throughout the summer, you'll be able to find a "weather window" that will allow you a pleasant and safe
passage.
The first thing you have to do, IMO, before you commit to
buying a boat in South Wales, is to get the proper nautical chart for the Bristol Channel and ALSO the tide and current tables. One isn't much good without the other. The second thing you have to do is learn to read them. Only then should you think of
buying the boat.
Maybe I'm stating the obvious here, but in a Nomad you CANNOT make headway against a four
knot current! Conversely, on a FOLLOWING four
knot current, you'll be making EIGHT knots over the ground and you can do the fifty miles in 50/8, i.e. a little over 6 hours! So timing your departure from Swansea becomes all-important :-)!
There's a little more to it than that, but you get the idea. Get the chart and the tables, then come back to us, and we will help you along :-)
All the best,
TrentePieds