Sadly, your story is not altogether surprising. We gave our son 2K and when he went for a mortgage to buy a house he was put through the wringer and we had to provide affidavits to help him placate "the system". All of this is allegedly to ensure money laundering does not happen. Meanwhile the British Government has for decades sold (for a relatively measly sum each) licences for money laundering from abroad. These licences are called Non-Dom Status and annually billions flow through the financial institutions and everyone knows it (the UK being quite heavily criticised abroad, but hey-ho). This is set to increase (Brexit, so it is said - hardship/shrinking normal business, freedom from scrutiny, etc.), and again everyone fully expects that. You, as an ordinary individual, likely have to accept that you are going to be shafted, hung, drawn and quartered.
I am not an expert but I would think it unlikely you will be able to move the money you mention any time soon. Prepare yourself for some very uncomfortable times.