Remember it is your vehicle and you can choose who repairs it. Many insurance companies have their own approved or recommended repairs and will tell you must use them. This is for their convenience not yours.

You are NOT obliged to have your car repaired at the insurance nominated garage.
Only one estimate is needed for the repairs to your vehicle. Your chosen repairer should provide you with and estimate identifying the repairs covered and the cost of  labour, parts and materials required to complete the repair.

Only if the Insurance Engineer and repairer cannot agree should an additional estimate be required
You will normally be expected to sign a collection note when collecting your vehicle. This does not affect your legal rights.
If you are vat registered you will need to pay the repairer the full value of the vat due on the repair bill.
Your policy excess is the amount you will need to pay towards the repair bill. The policy excess will be shown in your policy Document.
Some items that are partially worn may have to be replaced with new during the repair – you are getting something better than you had and you may need to make a contribution (betterment) based on the amount of wear that has taken place. You will need to pay this to the repairers along with your excess if applicable.