According to the former commissioner, whose role was equivalent to the current Conflict of Interest and Ethics Commissioner, as soon as a lobbyist is involved, a gift is unacceptable. You should therefore pay for any entry fee, your meal or anything else when a registered lobbyist is lobbying MPs from the House of Commons. Whether any actual lobbying takes place or not, a precedent has been established and we ask all MPs to pay for their own meals.
On June 20th, 2023. See this statement in context.