If your car is comprehensively insured, your insurers may advise you to use their approved repairers. If the claim is dealt with in this way, any repair problems can then be referred to your insurers.
The approved repairers may provide you with a courtesy vehicle; however this is normally subject to availability on a discretionary basis and is not an automatic entitlement unless your policy states otherwise.
If your car is insured third party only and the accident was not your fault, you may be able to recover the cost of its repair from the other party. Once the details of your claim are passed to the other party's insurer, they may offer to have the repairs to your vehicle done for you. However if they don't, you will need to recover the cost involved, along with any other uninsured losses.