A covenant can be released or modified by the original person who imposed the covenant on the title (eg. developer). You could contact the person/developer and ask for their requirements to have the covenant appropriately modified or released altogether. They would probably charge a fee for this.
If the above is not a possibility for whatever reasons then you could apply to the Land Tribunal to have the covenant modified, though this is not cheap or quick. Info here:-
If you take the risk and proceed without release or modification of the covenant then after the works have been carried out and no enforcement action has been taken then you can obtain a restrictive covenant indemnity insurance policy to cover the cost of enforcement action taken in the future. This does not prevent enforcement action being taken obviously but it does cover the loss you would suffer.
For example, were you to sell the property the purchaser's solicitors would ask for such a policy (in the event that consent was not obtained).
If you google "restrictive covenant indemnity insurance providers" you will be able to make inquiries with insurers. They will need a copy of the wording of the covenant, the nature of the contemplated breach, the date the covenant was imposed and details of the steps you have taken to contact the person with the benefit of the estate.
They are relatively cheap (approx £150 depending on the value of your property) and the benefit can be passed on to your successors in title. You will also need to contact your lender to gain their approval of the policy.
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