Please, be so kind to pay attention to these points
1) I want to know, whether there is any way in UK to receive a proof of sending a particular contents in the envelope ,ie proof of sending particular documents, rather than only a proof of sending the envelope as such, without a possibility to keep a documentary evidence of the contents, which is in the envelope in the moment of the envelope's handing over at the Post Office. If the possibility of receiving the documentary proof of sending particular contents exists in UK, I would also like to know the technical term for such documentary proof, and I would like to know what kind of legal professional (solicitor?, notary public?) I should ask for issuing such documentary proof.
2) The delivery of documents as such is not the main problem. I can use a Special Delivery or some courier services - as Border Agency in case of EEA3 (unlike in case of some other applications) categorically insists on using the post anyway. The main problem is, that Border Agency can lose the EEA3 application and supporting documents during the likely several quarters of their storing and processing in Liverpool.
3) What I want to invest money into is preventive bolstering my position for the scenario, when Border Agency have lost some or all of my supporting original documents, and perhaps even deny their very previous receival and refuse to cooperate in resolving the issue. As a layperson I would believe, that my keeping the documentary proof, that I have previously sent all the documents "now" (ie in such hypothetical situation) lost, and keeping the certified copies of the documents "now" lost, might enable taking a successful legal action against Border Agency in such bad circumstances. So, my question was, how to effectively and preventively invest £400-£600 (ie what sort of legal professional and what services exactly to ask for) before sending EEA3 with my original documents to Border Agency, to preventively bolster my position for the case, that the above described ominous scenario really happens in the future.
I understand the terms and conditions of this website, I won't hold you accountable for any possible inefficiency or negative consequences of your advice, but before accepting your answer, I would like to learn from you some at least potentially useful and non-banal suggestions.
Thank you in advance for your kind understanding and additional help.