Yes, she will have to apply for a visa,
I personally would apply for a fiance visa first. If the worst happens and she is denied then it is better that you are denied whilst you are only fiances rather than husband and wife.
If you wish to apply for a fiance visa so that you can marry here you must show that:-
You can find Uk immigration solicitors through the following Law Society Website search engine:-
You will need to apply for settlement (ie. fiance visa) by using VAF4 Settlement, available for download from UKBA's website. It would be best for either a solicitor in the UK to prepare it in consultation with both you and your wife before submitting it.
She will also have to pass the english language test to show that she has a basic command of english listening and spoken language. Everyday expressions and basic phrases and she will have to contact the Embassy before submitting to find out about approved test providers in the Ukraine..
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