The Government is currently advising against all travel to all regions of Ukraine.
For the full advice please see, https://www.gov.uk/foreign-travel-advice/ukraine.
Immediate family members of a British national (spouse, partner, children under 18, parents of a British national child under 18 or adult dependent living with a British national due to a medical condition) who normally live in Ukraine and intend to apply for a visa under the Family Migration route are advised to read this guidance on family migration visas and contact +44 (0) 300 3032785 for assistance before applying. Lines are open Monday – Friday 8am-8pm and Saturday and Sunday 9am-5.30pm. Further information on UK visas for those in Ukraine, including temporary visa concessions for some groups of visa applicants, can be found on the visas for those in Ukraine (https://www.gov.uk/guidance/support-for-family-members-of-british-natio…?) pages on gov.uk.