Yes, 54m.co.uk can receive emails.
Yes, 54m.co.uk seems to be a legitimate domain.
A record
18.220.167.252
MX records
alt1.aspmx.l.google.com
64.233.186.26
alt2.aspmx.l.google.com
209.85.202.27
aspmx.l.google.com
209.85.201.27
aspmx2.googlemail.com
64.233.186.27
aspmx3.googlemail.com
209.85.202.26
mailstore1.secureserver.net
72.167.238.32
smtp.secureserver.net
72.167.238.29