Don't worry at what you might call a lack of prep jumping, the secret to a successfull showjumping comp is schooling. What wins or makes a good round is what you do between the fences.
Your horse knows how to jump, it dosen't matter if you don't jump for a day, a week or a year - your horse will still remember how to get over the fences.
Actually it might not be a bad idea to get into the habit of NOT jumping a week or so leading up to a competition as your horse might get bored if you jump him to much. Many of the top grand prix horses are not schooled over fences at all, they just jump at competitions.
A perfect example of what I'm trying to say was an 11yr old mare I bought , she had been used all her life as a farm cart horse and had never been jumped at all yet here she is clearing 1.4m with ease , and i'd only worked her for about 1 month before this photo was taken. Olga (363).jpg
As for the scary jumps you can still lead your horse round them so he can get a good look , it's even possible to lay coloured poles on the floor and make him walk over them. It won't matter if they are 6 inches or 2Ft 6 inches - he will look at them the same.