A pension switch involves moving your funds from one pension scheme to another. Generally people transfer their pension to get better growth performance or to decrease charges and fees associated with their current scheme.
It is generally not a good idea to switch your pension if you are in a defined benefit scheme or have certain guarantees. A pension adviser can look at your arrangements and see if a switch would be a positive move.
Should your pension be open to a move (ie there are no benefits that make it a bad idea), an IFA can take a look at the performance and contact the scheme administrator to get projections and information on charges. The IFA can then compare those projections and charges to what is available on the market. They will then make recommendations, or tell you are best to stay put.
The IFA you use to guide you will charge fees, either out of your fund or as ongoing management charges. Good advisers will want to meet with you at an appropriate regular time interval (quarterly, bi-annually) to review where you are at and whether the pension is still appropriate to both you and the current economic climate. These reviews are important to make sure you are on track for retirement.