Planning to ride down to Gibraltar and back ... roughly follow the coast roads down through France, Spain and Portugal.
Any tips from anyone?
You'll have a great time, I'm sure. I spend a lot of time on the continent on bikes, and as long as you're prepared it's great fun. It gets better as you get more used to it. If I were going for the first time I'd probably prefer to go in a group, but there are swings and roundabouts to that. I don't really give it a second thought, and just jump on the bike and go on my own.
Make sure you stay legal, especially in Spain. The Spanish love to throw the book at you and if you get stopped for speeding and they've had a slow day they'll go over your bike and your documentation with a fine tooth comb, then hit you for any and every infringement they can find. You'll need the equipment that the various advisory bodies mention such as first aid kit, spare bulbs; you'll need back protection; you'll need good maps, and as long as you don't let it distract you GPS could definitely be an asset although I don't use it. The continentals rely a lot more than we do on navigating from town to town, which is a bit awkward until you get used to it. They very rarely if ever tell you directions like "north" and they don't rely so much on road numbers as the English do -- partly because every main road has so many different numbers that you don't have time to pick the right one off the sign before you've passed it. The colour coding of signs is a bit different from what you're used to in England and the arrows for directions on the signs are, well, variable. By which I mean "straight on" can have an arrow pointing up, down, or to either side depending on where they put it and how they felt on the day. The Spanish drive more, er, enthusiastically than we do in England, and the Portuguese still more so. Try not to get involved. I'd recommend high-vis kit. One of my helmets has a drop-down sun visor inside the main clear visor, it's great for sunny weather when you might for example go into a tunnel. You'll need a cloth or sponge to clean the bugs off your visor/windscreen/goggles. Carry water with you, there are some long stretches of open road with nothing for miles. Keep an eye on the fuel for the same reason. Obviously you could be using a lot of the tread from your tyres so they need to be good before you set out, but I won't bore you with all the other domestic stuff.
Biker is right, it's SOOOO easy to go into auto-pilot. I think I'm most at risk when there's a break in the routine. I have a sheet of paper that says "DRIVE ON THE RIGHT" written in fat felt-tipped pen that I can slip into my tank bag map pocket, for when I stop at a filling station and forget where I am on the way out. I've done that more times than I like to think but only caused one accident so far. It was an expensive mistake but it could have been a lot worse. It would have been a nightmare if I couldn't speak the language and hadn't had somewhere to stay. Fortunately I was riding solo, the protective gear did the job and I got away without a scratch. My insurance company still hasn't paid and it was nearly two years ago. Make sure your insurance and breakdown cover is adequate, even if you have to take out extra. Most policies only give a bare minimum. Check if you need to inform the insurer before the trip, for how long a trip it covers, what's covered etc.
It's a lot better getting to Gib on a bike than in a car. You can go past the queues of cars at the border. The Spanish hold them up something shocking. As has been said it's because they find The Rock an irritation. Can't really blame them, what would you think if Spain held the Isle of Wight?
I was on the barrier, right in the middle. Made us crack up as well 
