You should have two main options;
1 opt for a deferred pension in your existing scheme based on your service to date of leaving, or
2 take a transfer value to your new scheme
If you opt to leave a deferred pension in your old scheme it will be based on your service and salary at date of leaving , e.g 5/60ths x salary. And this deferred pension would be indexed at the lesser of CPI or 4% p.a up to retirement age.
Alternatively your existing scheme may offer you a transfer value to take to your new scheme. What the transfer value will provide in your new scheme is dependant on the structure of that scheme.
Deciding which is likely to be the best option is very difficult, not least since you have some 30 years to go to retirement. I would need to see the various numbers to come to some conclusion.