There are no real difficulties in organising a trip to Costa Rica. There are just a few adminisrative rules you need to respect.
- For a trip to Costa Rica you simply need to have a passport that is valid for one day after you leave Costa Rica. You won't need a visa if your trip doesn't exceed 90 days. If you want to stay longer then you should apply for a visa from the Costa Rican embassy in London. You should also be aware that before you are allowed to enter Costa Rica you will need to provide proof of onward travel or a return ticket. This is obligatory.
There are no obligatory vaccinations unless you have stayed in or travelled through a yellow fever country. If you have then a vaccination is indispensable and you will have to show your international vaccination card. You are also recommended to be vaccinated against typhoid, hepatitis A and rabies.
Like most travellers your have fallen for Costa Rica's charms and have decided to stay there for longer. Or you've decided to move and live there. It's quite possible but you need to fill in a complete dossier and have the patience of a saint. You can get a residency card by fulfilling all the requirements of the Dirección general de Migración y extranjeria. So when you finally decide to go home and start your life again with your family and friends, you will have to pay $29. This is the exit tax that everybody has to pay. The good news if you don't have any more cash is that you can pay it by credit card.
If you want to rent a car while you are there, then don't forget your international drivers licence. You can get it from the Post Office.