Well, government says it's winning:
Security minister Brandon Lewis said "The majority of migrants who attempt this journey are being stopped, only 25% have made it to the UK this year, compared with 48% last year."
https://www.bbc.co.uk/news/uk-england-kent-51420971
I'm not sure how the figures are arrived at (personally, if I were a successful clandestine migrant I'd keep schtum about it and Lewis would be none the wiser), not what the definition of 'made it to the UK' is.